372xp issues

[slambox28]

Hi, name is Brad, I have a 372 XP with the 52mm bore. Excellent saw, my favorite so far aside from: the choke lever catch not working, gotta use a homeade clip or use a stick. And occasionally the on/off switch won't kill it either, gotta use the choke. Otherwise, it is a beast and 10/10 favorite saw, got it from ebay used with a new rebuild/ big bore kit.

The issues: it seems like it locked up on me but it's not the cylinder or piston. Old fuel was used from an oil bottle that was 3 months old and expanded to split the bottle. So, the fuel was exposed to open air for months, but it certainly had oil.. the saw sat in a horse barn for several months with an open wall. It's crazy how much dust, sand and debris finds its way into crevices in a short timeframe.

I went to run the saw, it's dry so fuel is added. After adding fuel, then making sure the bar oil was full too or adequate level. Just one quick thing to cut, got it running and it ran enough to get hot even with this old, oxydized fuel from a split oil bottle. Got it warm to cut this piece of wood and out of nowhere it acts like it locked up; bogs down, shuts off and wont fire back up.. instantly I think the fuel was somehow no good even though it did for sure have oil mix.

The saw has a catch at one point of the rotation. Just one point not a resistance the whole rotation. It has this catch even with the bar taken off. Later on I install a new cylinder and piston kit and the exact same issue.. the one thing I haven't tried yet is to note at what point in assembly does this create the catch. The catch is not seeming to be the bottom and top end engine assembly as I've tested. The catch is not the pull handle when taken off. This happened just after getting hot enough to stay running when cutting through one board. The fuel was old and oxydized but had oil for sure.

Any ideas what could cause this on the 372xp? Gotta clean all the parts now to assemble again and get new piston rings for the original top end.. The farmertec top end kit has thicker piston rings than the one originally on it.

If findig out anything will keep posted

 

[slambox28]

Ahh I just got on YouTube, so far with "Tinman's saw" channel I've found out the aftermarket crankshaft and bearings are known to fail if it's a farmertec. Especially with the bigbore kit. The NWP is said to be a better variety of crank and bearings. I'm not sure what brand is in it now, gotta find that out. Also need to build a case splitter to split the case the "right" way. I'm likely going to need to use sealant in some areas on the crankcase mating surfaces where I probably gouged it with screwdrivers.

This saw is extremely filthy after sitting in the horsebarn, a hot tank dip would be nice but probably go with the air nozzel and brake cleaner to clean it up.

 

[cuinrearview]

Bump

 

[Woodslasher]

I'll bet that sticky feeling is the magnets on the flywheel passing the coil.

 

[Czed]

Pull the cylinder and check for bad crank bearings

 

[cuinrearview]

Pull the cylinder and check for bad crank bearings

If I read it right he already split the case with screwdrivers.

 

[Czed]

If I read it right he already split the case with screwdrivers.

I read he replaced the top end only
I don't know.

 

[cuinrearview]

I read he replaced the top end only
I don't know.

Post #2

 

[slambox28]

I think I've found the issue! Stretched the piston rod or the crankshaft and the piston is slightly hitting the top of the cylinder jug! This is very unexpected because the saw only got warmed up and to make one single cut on a cedar board. I'm thinking the culprit must be bad fuel! Fuel mix stored in an oil bottle that had split open from the pressure buildup. It sat outside for months in a truck bed and oxydation to the open air for several months. A culprit of the gutless power? Then adding too much additional oil to be sure it had lubrication. And even possibilities of water/ condensation in the fuel mix? No power at all, bogging down from the slightest touch to the board! High rpms with no pressure on the piston due to bogging down on contact. I was holding it at high rpms to make the cut, literally only able to graze the blade on the wood before bogging down. Out of nowhere it seemed like it for sure locked up on me! I couldn't believe it because this saw was a prize possession and amazed me every time using it, new rebuild kit, favorite saw I've ever used. I paid about 600 total for it. Hadn't got much use out of it yet. I never ever once considered this could happen. Lesson learned, lots of lessons learned.

The crankshaft is genuine Husqvarna, the bearings are like brand new, crank seems to be like brand new. I see nothing wrong with simply porting out the cylinder jug at this point for piston clearance. With a Turnado 17" engine lathe, turn out the top of the jug. Also porting out extra material for aerodynamic flow and then doing a single tube muffler mod (drill one hole and weld in one tube). Chalk it up to a "0.040" stroker-rod" modification. The cases are all genuine Husqvarna too, no Chinese clone. There is only one visible gouge I've seen (a rounded screwdriver shaft pry impression on the inside edge) on the case BUT it doesn't go all the way across the surface. It has to be some high-quality alloy aluminum. With porting it, the only parts I need to buy are the gaskets. No more piston tapping. I'm brand new to saws, this threw me for a loop. Expected I had bought an expensive clone. I knew nothing technical about the 372xp before at all, besides that it's said to be one of the all-time best saws.
For lathe turning: this cylinder kit is marked with a centerline indention on top to indicate center of the bore. And the 4 bolt down screws are not perfectly equal around the cylinder. 2 of them (side by side) are 1-5/8" from the center mark. The other 2 are 1-1/2" from center mark. The challenge will be making the holding fixture for the cylinder to turn it at center or adjustments to center it on the bore. Trying to minimize cost too and make a quick repair. Can't wait to get this saw back in operation!

 

[Czed]

I think I've found the issue! Stretched the piston rod or the crankshaft and the piston is slightly hitting the top of the cylinder jug! This is very unexpected because the saw only got warmed up and to make one single cut on a cedar board. I'm thinking the culprit must be bad fuel! Fuel mix stored in an oil bottle that had split open from the pressure buildup. It sat outside for months in a truck bed and oxydation to the open air for several months. A culprit of the gutless power? Then adding too much additional oil to be sure it had lubrication. And even possibilities of water/ condensation in the fuel mix? No power at all, bogging down from the slightest touch to the board! High rpms with no pressure on the piston due to bogging down on contact. I was holding it at high rpms to make the cut, literally only able to graze the blade on the wood before bogging down. Out of nowhere it seemed like it for sure locked up on me! I couldn't believe it because this saw was a prize possession and amazed me every time using it, new rebuild kit, favorite saw I've ever used. I paid about 600 total for it. Hadn't got much use out of it yet. I never ever once considered this could happen. Lesson learned, lots of lessons learned.

The crankshaft is genuine Husqvarna, the bearings are like brand new, crank seems to be like brand new. I see nothing wrong with simply porting out the cylinder jug at this point for piston clearance. With a Turnado 17" engine lathe, turn out the top of the jug. Also porting out extra material for aerodynamic flow and then doing a single tube muffler mod (drill one hole and weld in one tube). Chalk it up to a "0.040" stroker-rod" modification. The cases are all genuine Husqvarna too, no Chinese clone. There is only one visible gouge I've seen (a rounded screwdriver shaft pry impression on the inside edge) on the case BUT it doesn't go all the way across the surface. It has to be some high-quality alloy aluminum. With porting it, the only parts I need to buy are the gaskets. No more piston tapping. I'm brand new to saws, this threw me for a loop. Expected I had bought an expensive clone. I knew nothing technical about the 372xp before at all, besides that it's said to be one of the all-time best saws.
For lathe turning: this cylinder kit is marked with a centerline indention on top to indicate center of the bore. And the 4 bolt down screws are not perfectly equal around the cylinder. 2 of them (side by side) are 1-5/8" from the center mark. The other 2 are 1-1/2" from center mark. The challenge will be making the holding fixture for the cylinder to turn it at center or adjustments to center it on the bore. Trying to minimize cost too and make a quick repair. Can't wait to get this saw back in operation!

Did
You
Remove
The
Base
Gasket
And
Not
Have
Enough
Clearance
Just run it with a base gasket if you did.

 

[smokey7]

This post from the op has me all over the place. I don't know what to reply to first. If it always had clearance and then lost that clearance while running I'd bet a bearing is bad somewhere. If it were a prized possession why was it in a lean to horse barn for months and ran in a wide open to atmosphere jug of fuel? But machining the jug or adding clearance isn't going to fix your issue. Figure out what changed and fix that.

 

[Woodwackr]

I think I've found the issue! Stretched the piston rod or the crankshaft and the piston is slightly hitting the top of the cylinder jug! This is very unexpected because the saw only got warmed up and to make one single cut on a cedar board. I'm thinking the culprit must be bad fuel! Fuel mix stored in an oil bottle that had split open from the pressure buildup. It sat outside for months in a truck bed and oxydation to the open air for several months. A culprit of the gutless power? Then adding too much additional oil to be sure it had lubrication. And even possibilities of water/ condensation in the fuel mix? No power at all, bogging down from the slightest touch to the board! High rpms with no pressure on the piston due to bogging down on contact. I was holding it at high rpms to make the cut, literally only able to graze the blade on the wood before bogging down. Out of nowhere it seemed like it for sure locked up on me! I couldn't believe it because this saw was a prize possession and amazed me every time using it, new rebuild kit, favorite saw I've ever used. I paid about 600 total for it. Hadn't got much use out of it yet. I never ever once considered this could happen. Lesson learned, lots of lessons learned.

The crankshaft is genuine Husqvarna, the bearings are like brand new, crank seems to be like brand new. I see nothing wrong with simply porting out the cylinder jug at this point for piston clearance. With a Turnado 17" engine lathe, turn out the top of the jug. Also porting out extra material for aerodynamic flow and then doing a single tube muffler mod (drill one hole and weld in one tube). Chalk it up to a "0.040" stroker-rod" modification. The cases are all genuine Husqvarna too, no Chinese clone. There is only one visible gouge I've seen (a rounded screwdriver shaft pry impression on the inside edge) on the case BUT it doesn't go all the way across the surface. It has to be some high-quality alloy aluminum. With porting it, the only parts I need to buy are the gaskets. No more piston tapping. I'm brand new to saws, this threw me for a loop. Expected I had bought an expensive clone. I knew nothing technical about the 372xp before at all, besides that it's said to be one of the all-time best saws.
For lathe turning: this cylinder kit is marked with a centerline indention on top to indicate center of the bore. And the 4 bolt down screws are not perfectly equal around the cylinder. 2 of them (side by side) are 1-5/8" from the center mark. The other 2 are 1-1/2" from center mark. The challenge will be making the holding fixture for the cylinder to turn it at center or adjustments to center it on the bore. Trying to minimize cost too and make a quick repair. Can't wait to get this saw back in operation!

Measure the squish

 

[Czed]

Measure the squish

He did with the top of the piston.

 

[slambox28]

Did
You
Remove
The
Base
Gasket
And
Not
Have
Enough
Clearance
Just run it with a base gasket if you did.

No this happened mid near end of the cut. And I did put a new case gasket on the new kit. In fact got 5 or 10 of them

 

[Woodwackr]

No this happened mid near end of the cut. And I did put a new case gasket on the new kit. In fact got 5 or 10 of them

That wasn't the question...

 

[slambox28]

This post from the op has me all over the place. I don't know what to reply to first. If it always had clearance and then lost that clearance while running I'd bet a bearing is bad somewhere. If it were a prized possession why was it in a lean to horse barn for months and ran in a wide open to atmosphere jug of fuel? But machining the jug or adding clearance isn't going to fix your issue. Figure out what changed and fix that.

Man I'm very surprised by such quick replies! Only kept the saw in a lean-to barn because it leaks bar oil! I didn't try addressing it otherwise would be in the house(I assumed a difficult fix, too good to have it not leaking inside the house). Found out on YT recently it can be fixed by loctite 515 on the pickup tube connection going to the pump. At the time didn't think about the fuel being bad, Engine oil bottle for "free" fuel storage (could've maybe put a hole in the lid but didn't know about the expansion at the time). Short term storage turned long term storage. At the time didn't think fuel was causing the issue, thought it just needed warmed up. This is from over a year ago. Then got carried away, "just one cut on a 2x12 rough cut cedar board"-famous last words.

Bearings: Crank bearing are in like new condition all around. The piston rod bearings have no play in any forward or back movement but some wobble in the side load; likely something normal being roller bearings with a plastic collector sleeve. No bearing slack anywhere whatsoever push or pulling forces. Just the side load wobble on the piston rod bearing. The piston taps when cold too, not just from getting hot.

There is not even a hint of side movement on the crank bearings; even with the crank still in one & stuck in the case, moving it there's no side load play anywhere at all for crank bearings. No play of any kind with crank bearings, like brand new out of the box.

The cranks shaft rotates straight and true to the naked eye, no types of signs or movements indicating the crankshaft is bent at the point of piston contact. Maybe with the 52mm kit it did stretch something? But if it's working square and true no signs of damage to run it stretched?

The only thing I can put a finger on is that the piston rod or some part of the crank stretched. A very unexpected cause for a newbie at the time. I'm connecting the dots now over a year later.
High rpm with no load (not pegged out just high rpms while still requiring full throttle), this was just to build momentum to cut this one cut. Engine bogging, flooding the engine. Then releasing all load to build rpms again always near full throttle BUT not pegged out; building EGT temps too? Gets hot enough overtime something stretches and finally does hit the cylinder after several minutes?

Wouldn't have put 2and2 together at the time, it didn't seem like a possibly damaging thing to do at the time at all with having extra oil added straight to the tank for sure lubrication. Complete newbie, and never taken one apart before, not aware of any of this new information.

With lots of cutting opportunity coming up I think it'd definitely be a very good idea to replace crank assembly and bearings. BUT this job is not time sensitive more of project. I'd like to get use out of new condition bearings and a genuine crankshaft. It might just last nearly as long as new parts will. Now I know how to prevent this from happening again too: use newer fuel to keep a load on the saw at all times of higher rpms. And an exhaust mod for low temps. It's really appealing to shave out the cylinder and run all the same parts. Plus shaving out extra for hp and flow. Stretching a piston rod or part of the crank seems like no issue if it's still square and bearings are mint as ever.

Maybe I'll buy the parts for stand-by but run these older parts until failure. No signs of issues with anything besides piston tapping, I cant think of any way shaving out the cylinder for clearance will cause further damages. The bearings are ok for sure after lots of testing, actually new condition

I really don't wanna have to have problems again BUT it seems like I will be using parts equal to brand new without buying new parts. And now with the knowledge to prevent it from happening again most importantly!

 

[slambox28]

That wasn't the question...

WHen I swapped a new jug on it I used a new case gasket for sure, correct. sorry

 

[slambox28]

Measure the squish

Ahh ok the squish is the clearance. I'll send the "measurement"

 

[slambox28]

Here is the contact impression on the piston. Taking material off the piston face could work too. Much easier and quicker but without the benefits of porting.

 

[slambox28]